With reference to FIG. 1, as is known in the art, the Public Switched Telephone Network (PSTN) 10 includes mechanisms for directing certain calls, such as an enhanced emergency 9-1-1 (E 9-1-1) call, to a Public Safety Answering Point (PSAP) 20. For example, consider an end office (EO) 30 serving Customer premises equipment (CPE) 40 (i.e., a telephone or other like CPE) from which an E 9-1-1 call is placed. The EO 30 commonly includes a telecommunications switch 32 (e.g., a class 5 switch such as the Lucent Technologies 5ESS or another like switch) that is operatively connected to the CPE 40. When the switch 32 recognizes an E 9-1-1 call, the call is routed, e.g., over the PSTN 10, to the PSAP 20 serving the geographic region in which the CPE 40 is located, optionally, said PSAP 20 being designated by a directory number (DN) assigned thereto.
While only one CPE is shown, it is to be appreciated that typically a plurality of similarly situated CPE are likewise served by the EO 30 and switch 32. Optionally, if the switch 32 serves multiple CPE in different geographic regions served by different PSAPs, a selective router (SR) 34 (access via the PSTN 10) is employed to route E 9-1-1 calls to the appropriate PSAP. For example, the switch may query a localized database of the SR 34 which relates the DN of the calling CPE to the DN of the PSAP that serves the geographic region in which the CPE is located. In this manner, the E 9-1-1 calls can be directed to the appropriate PSAPs. More frequently, the EO switch may route the call to a tandem office which may then query a localized database of the SR 34 which relates the DN of the calling CPE to the DN of the PSAP that serves the geographic region in which the CPE is located. In this manner, the E 9-1-1 calls can be directed to the appropriate PSAPs.
Typically, upon receiving an E 9-1-1 call, the PSAP 20 queries an Automatic Line Identification (ALI) database (DB) using the DN of the calling CPE 40. The ALI DB provides the PSAP 20 with information associated with the DN of the calling CPE 40, such as: the geographic and/or physical location of the CPE 40 (i.e., a street address or other positional identification); optionally, any special conditions (e.g., medical conditions of the CPE's registered owner or user, repeat call patterns from the CPE 40, etc.); and/or any other such relevant information. In this manner, a proper response to the E 9-1-1 call can be quickly and readily coordinated.
One of the advantages of what is known as voice-over-packet-network telephony (which includes, but is not limited to Voice over Internet Protocol (VoIP) telephony) is the ability for “remote” users to access the PSTN through their “home” access network and/or switch. This is a beneficial arrangement since other callers can still reach the user by dialing their normal DN. For example, an individual (i.e., a remote user) that is traveling (e.g., in Cleveland, Ohio) or otherwise away from their home office or location (e.g., in Phoenix, Ariz.) may still be reached at their normal DN (i.e., their Phoenix number). Similarly, calls made by the remote user appear to come from their normal DN (i.e., their Phoenix number) and benefit from showing that DN on a caller ID. Further, the remote user has the ability to utilize any Private Branch Exchange (PBX) or Centrex features supported by the home location, home access network and/or home switch.
While generally acceptable for its intended purpose, the foregoing approach for handling emergency calls has certain drawbacks, in particular when dealing with VoIP emergency calls initiated by roaming and/or remote users. That is to say, e.g., when the aforementioned remote user is accessing the PSTN via their home access network and/or home switch in Phoenix, an E 9-1-1 call placed by the remote user would appear to be coming from their normal DN in Phoenix which is associated with their home location (i.e., Phoenix). Accordingly, the PSAP serving the home location in Phoenix would receive the E 9-1-1 call. However, the remote user is actually in Cleveland. Therefore, it would be advantageous to in fact have the E 9-1-1 call directly routed to an appropriate PSAP serving the remote user's location in Cleveland.
Accordingly, a new and improved system and/or method for handling VoIP E 9-1-1 calls is disclosed that overcomes the above-referenced problems and others.